YTHDF1-N6-methyladenosine-ARHGEF2 axis promoted colorectal tumorigenesis and metastasis

N6-methyladenosine (m6A) governs the fate of RNAs through m6A readers. Colorectal cancer (CRC) exhibits aberrant m6A modifications and expression of m6A regulators. However, little is known about how m6A readers interpret oncogenic m6A methylome for malignant transformation. m6A reader YTHDF1 was overexpressed by copy number gain/amplification in majority of CRCs. YTHDF1 high expression and CNVs predict increased risk of CRC relapse. Transcriptome profiles of YTHDF1-high tumors exhibit highly metastatic features. YTHDF1 promoted CRC tumor cell and organoid proliferation and enhanced metastasis. Ythdf1 knockout dampened tumor growth in carcinogen-induced CRC model. Through multiomic integration, RhoA activator ARHGEF2 was characterized as the key functional YTHDF1 target based on its m6A and YTHDF1-binding signal, translation efficiency changes, protein correlations with YTHDF1 in clinical samples, and disrupted RhoA features by YTHDF1 knockdown. Moreover, YTHDF1-ARHGEF2 co-regulation was observed in YTHDF1-overexpressing metastatic sites and carcinogen-induced Ythdf1-null CRC tumors. ARHGEF2 overexpression significantly rescued RhoA signaling, tumor cell survival and invasiveness impaired by YTHDF1 knockdown both in vitro and in vivo, further confirming the essential function of ARHGEF2. Multiomic analysis including RNA-seq, m6A MeRIP-seq, YTHDF1 RIP-seq and quantitative proteomics was performed to key YTHDF1 targets responsible for YTHDF1-mediated transformation.